Malignant

A new field of transfusion medicine, cell therapy, has developed with the better understanding of the function of different cell types ia the body. In cell therapy, various malignancies are treated by transfusion of specific cell types from blood. Therefore, more and more specialized methods for separating blood iato the various components are required. 

They release adenosine diphosphate [58-64-0 (ADP) and thromboxane [57576-52-0] which results in vascular contraction and, indirectiy, in the formation of fibrin clot. Platelet transfusions are indicated for patients with thrombocytopenia, ie, a shortage of healthy platelets or thrombocytopathy, ie, platelet malignancy associated with spontaneous hemorrhages. 

J. P. Dutcher, "Platelet Transfusion Therapy in Patients with Malignancy," in J. P. Dutcher, ed.. Modem Transfusion Therapy, CRC Press, Boca Raton, Ha., 1990. 

J. P. Dutcher, "Granulocyte Transfusions in Patients with Malignancy," in Ref 5. 

Interferons (lENs) (52,53), a family of species-specific vertebrate proteins, confer nonspecific resistance to a broad range of viral infections, affect cell proliferation, and modulate immune responses. AH three principal interferons, a-interferon (lEN-a) produced by blood leucocytes, P-interferon (lEN-P) by fibroblasts, and y-interferon (lEN-y) by lymphocytes, also have antiviral activity. The abiUty of interferons to inhibit growth of transplantable and carcinogen-induced tumor led to research showing the direct antiproliferative and indirect immune-mediated antitumor activities (see Chemotherapeutics, anticancer). IENs have been found to be efficacious in certain malignancies and viral infections, eg, hairy cell leukemia (85% response) and basal cell carcinoma (86% response). However, the interferons do have adverse side effects (54). 

Cancer. Cancer is a cellular malignancy characterized by loss of normal controls resulting in unregulated growth, lack of differentiation, and the abihty to invade local tissues and metastasize. Most cancers are potentially curable, if detected at an early enough stage. The ideal antineoplastic agent would destroy cancer cells without adverse effects or toxicities to normal cells. No such dmg exists. 

The active immunotherapeutic approach is specific and based on the premise that tumor antigens are immunogenic and the host is sufficientiy immunocompetent to mount an effective immune response to an autologous tumor. Theoretically, a weak or suppressed host immune system that had allowed the formation of a tumor may be overridden by active immunization or immunostimulation. In practice, vaccines composed of so-called autologous tumor extracts have been used to treat patients with malignant melanoma (73), and purified melanoma tumor-associated antigens have been used to ehcit antibody responses in melanoma patients (74). 

Nonspecific immunosuppressive therapy in an adult patient is usually through cyclosporin (35), started intravenously at the time of transplantation, and given orally once feeding is tolerated. Typically, methylprednisone is started also at the time of transplantation, then reduced to a maintenance dose. A athioprine (31) may also be used in conjunction with the prednisone to achieve adequate immunosuppression. Whereas the objective of immunosuppression is to protect the transplant, general or excessive immunosuppression may lead to undesirable compHcations, eg, opportunistic infections and potential malignancies. These adverse effects could be avoided if selective immunosuppression could be achieved. Suspected rejection episodes are treated with intravenous corticosteroids. Steroid-resistant rejection may be treated with monoclonal antibodies (78,79) such as Muromonab-CD3, specific for the T3-receptor on human T-ceUs. Alternatively, antithymocyte globulin (ATG) may be used against both B- and T-ceUs. 

A principal appHcation for photomedicine is the photodynamic treatment of cancer. Photochemical and clinical aspects of this topic have been reviewed (10,11). Direct irradiation of tumors coupled with adininistration of a sensitizer is used to effect necrosis of the malignancy. In this process, an excited state sensitizer interacts with dissolved in vivo to effect conversion of the oxygen from its triplet ground state to an excited singlet state, which is highly cytotoxic. In principle, excited sensitizers in either the singlet or the triplet state can effect this conversion of molecular oxygen (8). In... 

Among the aromatics, it was found that 4-nitroquinoline N-oxide [56-57-5] is a powerful carcinogen producing malignant tumors when painted on the skin of mice (80). It was further estabUshed that the 2-methyl, 2-ethyl, and 6-chloro derivatives of 4-nitro quinoline oxide are also carcinogens (81). 

Nuclear medicine studies may reveal information that is primarily anatomic in nature, or indicate the function of an organ on a regional basis (Table 1). These studies may be intended to identify new disease, confirm or deny suspected disease, or foUow the progress of treatment or the course of disease. The diseases may be relatively benign or extremely serious and can range from widespread medical problems such as ischemic heart disease to rarities such as Legge-Perthe s disease and malignant pheochromocytoma (7). 

Not only is TCDO a potent therapeutic agent in acute radiation syndrome, but treatment using TCDO from days 4—11 after TBI increases the survival rate in rats for up to one year, protects against the development of late GI ulcers, and also reduces the development of y-ray-induced leukemias and malignant epitheHal tumors, but not sarcomas (202). The anticarcinogenic effect of TCDO maybe related to the inhibition of PGs, which promote carcinogenesis, or to immunostimulation, which may result in a more effective elimination of malignant cells. 

Persistent effects do not resolve, and may even become more severe after removal from the source of exposure. They can occur as a consequence of acute or repeated-exposure conditions. Thus, the use of the term persistent should be clearly differentiated from the implication of the use of the description of an effect as chronic. It should be noted, however, that some chronic effects may be persistent an example is malignant neoplasia. 

Y. Mi shim a, The Second Japan-Mustralia International Workshop on Thermal Neutron Capture Therapyfor Malignant Melanoma, Vol. 2—4, Kobe, Japan, 1989, pp. 223-386. 

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